For those making a RPG, I've made a free node-based conversation editor. You can download it from my site. There is also a zip file with the gui and scripts it was intended to work with - might be broken, might need "massaging".
The editor is node-based, drag-n-drop, pretty easy to use, and runs on Windows. Should work on Win7 or later, should work on x86 or x64 versions. The documentation is here.
It can save "work in progress" conversations - but at the moment it insists on all node connectors being hooked up before save or export. I'll have to change that because it occurs to me that it has tremendous annoyance potential.
It currently exports to TorqueScript only. I'm in the process of restructuring the plugin system so that more functionality is placed in the plugin - this should give plugin authors more power and flexibility.
Obligatory screen shot: